namespace Yw.WpfUI.Hydro
{
    /// <summary>
    /// 抽象选择辅助类
    /// </summary>
    internal class LogicalSelectionHelper
    {
        /// <summary>
        /// 
        /// </summary>
        public LogicalSelectionHelper(HelixViewport3D viewport)
        {
            _viewport = viewport;
        }

        /// <summary>
        /// 选择改变事件
        /// </summary>
        public event Action<List<LogicalVisual3D>> SelectionChangedEvent;
        /// <summary>
        /// 状态改变事件
        /// </summary>
        public event Action<LogicalVisual3D, bool> StateChangedEvent;

        private readonly HelixViewport3D _viewport;//三维组件

        /// <summary>
        /// 选择集合
        /// </summary>
        public List<LogicalVisual3D> Selection
        {
            get { return _selection; }
            private set { _selection = value; }
        }
        private List<LogicalVisual3D> _selection = new();

        #region 内部实现

        //添加选择
        private void AddToSelection(LogicalVisual3D visual)
        {
            if (_selection.Contains(visual))
            {
                return;
            }
            _selection.Add(visual);
            this.StateChangedEvent?.Invoke(visual, true);
        }

        //从选择中移除
        private void RemoveFromSelection(LogicalVisual3D visual)
        {
            if (!_selection.Contains(visual))
            {
                return;
            }
            _selection.Remove(visual);
            this.StateChangedEvent?.Invoke(visual, false);
        }

        //清理选择
        private void ClearSelection()
        {
            if (_selection.Count < 1)
            {
                return;
            }
            _selection.ForEach(x => this.StateChangedEvent?.Invoke(x, false));
            _selection.Clear();
        }

        #endregion

        /// <summary>
        /// 处理单个选择
        /// </summary>
        public void HandleSingle(Point pt)
        {
            var logicalVisual = _viewport.FindNearestVisual(pt) as LogicalVisual3D;
            if (logicalVisual == null)
            {
                if (_selection.Count > 0)
                {
                    ClearSelection();
                    this.SelectionChangedEvent?.Invoke(null);
                }
                return;
            }
            if (_selection.Count == 1 && _selection[0] == logicalVisual)
            {
                return;
            }
            ClearSelection();
            AddToSelection(logicalVisual);
            this.SelectionChangedEvent?.Invoke(_selection);
        }

        /// <summary>
        /// 处理多个选择
        /// </summary>
        public void HandleMulti(Point pt)
        {
            var logicalVisual = _viewport.FindNearestVisual(pt) as LogicalVisual3D;
            if (logicalVisual == null)
            {
                return;
            }
            if (_selection.Contains(logicalVisual))
            {
                return;
            }
            AddToSelection(logicalVisual);
            this.SelectionChangedEvent?.Invoke(_selection);
        }

        /// <summary>
        /// 选择Visual
        /// 不触发选择改变事件
        /// </summary>
        public void SelectVisual(LogicalVisual3D visual)
        {
            ClearSelection();
            if (visual == null)
            {
                return;
            }
            AddToSelection(visual);
        }

        /// <summary>
        /// 选择Visuals
        /// </summary>
        public void SelectVisual(List<LogicalVisual3D> visuals)
        {
            ClearSelection();
            if (visuals == null || visuals.Count < 1)
            {
                return;
            }
            visuals.ForEach(AddToSelection);
        }
















    }
}